From Beckmann rearrangement

Using this pulse sequence to estimate the nature of derivatization of Suwannee River fulvic acid with N-enriched hydroxylamine to leam more about the carbonyl functionality of fulvic acid, Thom et al.(76) obtained signals for the primary products as oximes. Additional signals of secondary products arising from Beckmann rearrangements of the initial oxime derivatives were identified as nitriles, secondary amides and lactams. The bands assigned to hydroxamic acid result from a reaction of esters with NH2OH and are evidence for the presence of esters in the fulvic acid. 

Scheme S.18 Nitrogen heterocycle formation from Beckmann rearrangement reaction.

Beckmann rearrangement of cvc7ohexanone oxime. M.p. 68-70 C, b.p. I39 C/12 mm. On healing it gives polyamides. Used in the manufacture of Nylon[6]. Cyclohexanone oxime is formed from cyclohexane and niirosyl chloride. U.S. production 1978 410 000 tonnes, capryl alcohol See 2-octanol. caiH Uc acid See oclanoic acid. 

Beckmann rearrangement of benzophenone oxime to benz-anilide. Dissolve 2 g. of benzophenone oxime in 20 ml. of anhydrous ether in a small conical flask and add 3 g. of powdered phosphorus pentachloride (or 3 ml. of pure tbionyl chloride). Distil off the solvent and other volatile products on a water bath CAUTION ether), add 25 ml. of water, boil for several minutes and break up any lumps which may be formed. Decant the supernatant liquid, and recrystallise, in the same vessel, from boiling alcohol. The product is benzanilide, m.p. 163° confirm this by a mixed m.p. determination with an authentic specimen. 

Ingredients. Nylon-6 is produced commercially from caprolactam [105-60-2] which is the most important lactam industrially. AH industrial production processes for caprolactam are multistep and produce ammonium sulfate [7783-20-2] or other by-products. Approximately 95% of the world s caprolactam is produced from cyclohexanone oxime [100-64-1] via the Beckmann rearrangement (144). The starting material for cyclohexanone can be... 

Cyclohexanone oxime is converted quantitatively to caprolactam by Beckmann rearrangement in the presence of oleum, which is of sufficient strength to consume the several percent water in the molten oxime. The reaction mass is neutralized with aqueous ammonia to a cmde caprolactam layer and a saturated solution of ammonium sulfate. Approximately 1.5 kg of the total 4.4 kg ammonium sulfate per kilogram of caprolactam is produced in this step. Purification is by multistage vacuum crystallization from aqueous solution in neatly quantitative yield. 

Toray. The photonitrosation of cyclohexane or PNC process results in the direct conversion of cyclohexane to cyclohexanone oxime hydrochloride by reaction with nitrosyl chloride in the presence of uv light (15) (see Photochemical technology). Beckmann rearrangement of the cyclohexanone oxime hydrochloride in oleum results in the evolution of HCl, which is recycled to form NOCl by reaction with nitrosylsulfuric acid. The latter is produced by conventional absorption of NO from ammonia oxidation in oleum. Neutralization of the rearrangement mass with ammonia yields 1.7 kg ammonium sulfate per kilogram of caprolactam. Purification is by vacuum distillation. The novel chemistry is as follows ... 

Beckmann rearrangement, 6, 156 Isothiazole, 3-alkoxy-tautomerism, 6, 145 Isothiazole, alkyl-bromination, 5, 58 Isothiazole, 3-alkyl-5-amino-synthesis, 6, 166 Isothiazole, alkylthio-mass spectra, 6, 142 Isothiazole, amino-azo dyes from, 1, 330 tautomerism, 6, 157 Isothiazole, 3-amino-synthesis, 5, 135 tautomerism, 6, 146 Isothiazole, 4-amino-azo dyes from, 6, 175 diazotization, 6, 158 methylation, 5, 95 quaternization, 6, 158 reactions... 

The conversion of cyclohexanone to cyclohexanone oxime is brought about by the use of hydroxylamine sulphate. The sulphuric acid is neutralised with ammonia to ammonium sulphate and this is separated from the oxime. In the presence of oleum the oxime undergoes the process known as the Beckmann rearrangement to yield the crude caprolactam. After further neutralisation with ammonia the caprolactam and further ammonium sulphate are separated by solvent extraction (Figure 18.7). 

The ready availability and low cost of A -20-keto steroids from the degradation of sapogenins has led to intensive study of methods for the preparation of androstanes via these intermediates. The simplest, most practical and most widely used method on a production scale is the Beckmann rearrangement of -20-oximinopregnenes ... 

Substituents R, R at the starting oxime 1 can be H, alkyl, or aryl. The reaction conditions for the Beckmann rearrangement often are quite drastic (e.g. concentrated sulfuric acid at 120 °C), which generally limits the scope to less sensitive substrates. The required oxime can be easily prepared from the respective aldehyde or ketone and hydroxylamine. 

The ketoxime derivatives, required as starting materials, can be prepared from the appropriate aromatic, aliphatic or heterocyclic ketone. Aldoximes (where R is H) do not undergo the rearrangement reaction, but rather an elimination of toluenesulfonic acid to yield a nitrile. With ketoxime tosylates a Beckmann rearrangement may be observed as a side-reaction. 

The reaction that normally occurs on treatment of a ketoxime with a Lewis or proton acid is the Beckmann rearrangement (18-17) fragmentations are considered side reactions, often called abnormal or second-order Beckmann rearrangements. Obviously, the substrates mentioned are much more susceptible to fragmentation than are ordinary ketoximes, since in each case an unshared pair is available to assist in removal of the group cleaving from the carbon. However, fragmentation is a side reaction even with ordinary ketoximes and, in cases where a particularly stable carbocation can be cleaved, may be the main reaction. ... 

Benzoxazoles are produced in high yield from a-acylphenol oximes by a Beckmann rearrangement using zeolite catalysts <95SC3315>. The reaction of the o-benzoquinone 40 with aromatic aldehyde oximes produces the benzoxazoles 41 <95ZOR1060>. The fused oxazolium salts 43 (R = Me, Et, Pr , or Ph R2 = Me or Pr ) are formed from tropone and nitrilium hexachloroantimonates 42 <96JPR598>. 

Regioselective Beckmann rearrangements were used as key steps in the synthesis of phosphonoalkyl azepinones (Scheme 36) [43b] and in a formal total synthesis of the protein kinase C inhibitor balanol (Scheme 37) the optically active azide 197 derived from cyclohexadiene mono-oxide was converted into ketone 198 in several steps. After preparation of the oxime tosylates 199 (2.3 1 mixture), a Lewis acid mediated regioselective Beckmann rearrangement gave the lactams 200 and 201 in 66% and 9% yield, respectively. Lactam 201 underwent a 3-e im-ination to give additional 200, which served as a key intermediate in a balanol precursor synthesis (Scheme 37) [43 cj. 

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